In recent years, as a counter-measure against global warming and the future depletion of petroleum, fuel cell vehicles that drive using electric power supplied from a fuel cell system are under development. Such fuel cell vehicle has a fuel cell stack in which a plurality of fuel cells is connected in series, and a boost converter that outputs electric power by increasing output voltage of the fuel cell stack.
Usually, both the fuel cell stack and the boost converter are arranged in a space below the floor panel in order to ensure a large seating space for passengers. As described in Patent Document 1 indicated below, one possible arrangement is for the fuel cell stack and boost converter to be stored in a single housing and the housing to be arranged in a space below the floor panel.
However, a protection bar for suppressing distortion of the vehicle in a side crash is arranged below the floor panel in the left-right direction of the vehicle. Thus, when the fuel cell stack and boost converter are stored in a single large housing, arranging such housing in a space below the floor panel is difficult because the housing and the protection bar interfere with each other.
In order to avoid interference with the protection bar, it is necessary to store the fuel cell stack in a different casing (fuel cell casing) from that of the boost converter and to arrange the fuel cell casing rearward of the protection bar in the vehicle while arranging the boost converter forward of the protection bar in the vehicle. The reason for arranging the boost converter forward of the fuel cell stack in the vehicle is that the electric power output from the boost converter need to be supplied to a traction motor which is arranged at the front of the vehicle.
The fuel cell stack and boost converter arranged as set forth above need to be electrically connected to each other in a space therebetween, namely, a space above or below the protection bar. Here, the mass of the fuel cell stack is larger than that of the boost converter, and the fuel cell stack and boost converter accordingly have different vibration systems (natural frequencies) from each other. Thus, from the point of view of the durability of their electrical connection alone, connecting them with a flexible braided bus bar is one option. However, braided bus bars are expensive and it is thus desirable to use a plate-like bus bar from the viewpoint of suppressing an increase in cost.
Considering the above, in a practical and desirable configuration, the fuel cell casing and the boost converter are fastened and fixed to each other in a space above or below the protection bar, and electrically connected to each other using a plate-like bus bar, in such a manner that the fuel cell casing and the boost converter vibrate as a unit wherever possible (i.e. their vibration systems conform to each other).